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Native re-vegetation & weed collecting in Wellington’s greenbelt

I recently tagged along with Wellington City Council’s Environment Partnership Leader, Tim Park to visit some native re-vegetation sites in Wellington’s town belt.

Why is Wellington City planting native plants?

Wellington City Council has a policy of replacing pine forest with native plantings in the town belt as pine trees die or are toppled by wind. To me this seems like a very cost effective and achievable way of gradually increasing Wellington’s biodiversity. Along with increasing biodiversity, the more diverse and compact structure of native forest will be more stable for Wellington’s windy climate.

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What makes a successful planting?

First, you need to plant the right species. Karamu, makomako, ngaio and totara are examples of hardy species that grow quickly.

Tim Park was there to audit the planting sites. This means broadly monitoring the success of the native plantings. Criteria of successful plantings include how healthy plants are, how much of the site the plants are covering and potential competition from exotic plants (or weeds). He was also interested in natural native regeneration. Natural native regeneration is evidence of a recovering natural ecosystem through bird or wind dispersed seed, soil health and low weed competition.

How were the plantings doing?

We visited two planting sites on the hills between Newtown and Melrose. One was first planted in 2001, with over 5000 plants planted since. The other site was planted in 2010 with over 7000 plants planted in total.

The overall impression was the plants were doing great, but weedy competition was certainly a threat. As the plants mature the weed issues change. Weedy trees & shrubs such as sycamore, pine and broom threaten the quick establishment of native plants early on. Once a closed canopy stage is reached, shade tolerant vines, such as banana passion fruit and jasmine threaten to smother established plants. On-going management is required, along with educating the public about not dumping garden cuttings.

A WCC planting site established in 2010, with a north-west-west aspect. Image: Antony Kusabs, Te Papa, October 2015.

A WCC planting site established in 2001 with a north-east aspect. Image: Antony Kusabs, Te Papa, October 2015.

Weed collecting for Te Papa’s collection

This WCC planting audit was a good chance for me to collect some weed specimens for Te Papa’s plant collection (or herbarium). The herbarium has been collecting plants for 150 years, but despite having good collections of most native species from the Wellington region, many weed species are underrepresented in the collection. Sometimes, this can be because certain plant species haven’t been weedy in Wellington for very long.

Why collect plant specimens?

Herbarium collections provide important voucher specimen records which, collectively, tell researchers what grows where in New Zealand. This information can then be used by land managers to manage conservation and weed issues on the ground.

What else is Wellington City Council up to in the world of plant conservation?